1. Field of the Invention
The invention relates to an electron accelerator with a target exposed to the electron beam for the production of x-ray deceleration radiation. A collimator is arranged behind the target in the beam direction having a passageway of fixed dimensions sufficient for maximum adjustable beam cone dimensions. Adjustable x-ray aperture plates are positioned behind the collimator and an electron absorber is positioned behind the target in the beam direction.
2. Description of the Prior Art
For the production of x-rays, a target, which may comprise a plate of several mm thickness and made of heavy metal, preferably tungsten, is placed into the electron beam of the electron accelerator. The thickness of the target represents a compromise. If the target is selected too thin, insufficient x-ray quanta will be produced. If the target is selected too thick, an undesirable number of x-rays will be absorbed in the target itself. Furthermore, the maximum of the energy spectrum is then shifted towards the long-wave range. In order to prevent electrons from passing through the target having a prior art thickness into the x-ray cone, it is known in the art to place so-called electron absorbers directly behind the target into a boring of a target sled which also retains the target. For example, an absorption member made of copper or another metal of a medium atomic number may be inserted in order to receive superfluous electron radiation but which only slightly weakens the x-rays produced in the target. There is the disadvantage, however, that additional x-ray quanta are produced by electrons in the material of the electron absorber. These x-ray quanta have another origin than the radiation quanta produced in the target and are of a lower energy. Consequently, they are medically undesired and increase a half-shadow region at the margin of the x-ray cone or width of the radiation.